Na_5,Na_6和Na_7团簇光学吸收谱的理论研究

Optical absorption spectra of Na_5,Na_6 and Na_7 clusters:a theoretical study

以含时密度泛函理论为基础,结合从头赝势方法运用含时局域密度近似计算了Na5,Na6和Na7团簇的动力学极化强度,并通过傅里叶变换得出了团簇的光学吸收谱.研究表明,计算结果可以较好地再现实验谱,而且Na6和Na7团簇的结果和组态相互作用的结果符合较好.二维结构和三维结构的Na6团簇的计算结果表明,只有二维结构可出现低于2eV以下的峰,而且二维结构光谱的计算结果与实验结果符合较好.

In the frame of time-dependent density functional theory, the dynamical polarizabilities of Na5, Na6 and Na7 clusters are calculated using a time-dependent local density approximation. By using Fourier transformation, the optical absorption spectra of Na5 , Na6 and Na7 clusters are obtained from their dynamical polarizabilities. It is shown that experimentally measured optical absorption spectra of Na5, Na6 and Na7 clusters are reproduced in our calculations. Furthermore, the calculations of Na6 and Na7 clusters are in good agreement with the results of configuration interaction method. Compared with the three-dimensional structure of Na6, the calculated optical absorption spectra of Na6 with the two-dimensional structure are more close to the experimental data.